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Another Method of Drawing Lines Perpendicular to Each Other at Common Angles.

closely can derive much benefit from the knowledge of the subject gained.

If two lines are to be perpendicular to each other at common angles, such as 30 deg., 45 deg. and 60 deg., the problem is simple, and may easily be seen by reference to Fig. 27.

The line AB is drawn at 30 deg. with

GH will be the line desired.

This latter statement may often be put to use, as we may see from Fig. 28. In making drawings of plumbing work, it is far oftener the case that a branch is taken from a horizontal or vertical line of pipe than from a line running at odd angles. A regular Y branch is always

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The Main Pipe Drawn With a Tee Square-Lines of Branch With 45 Degree Triangle.

the horizontal, and can be obtained simply by drawing a line along the edge of the 30 deg. triangle placed against the tee square. To obtain a line at right angles to AB just reverse triangle No. 1 to the

at an angle of 45 deg. with the main line of pipe. Therefore, in laying out work, such as shown in Fig. 28, the main pipe is drawn in with the tee square, and the lines of the branch are drawn in with

the use of the 45 deg. triangle in position No. 1. Lines representing the hubs are put in with the same triangle in position No. 2.

In Fig. 29 we show right and wrong methods for drawing quarter and eighth bends, and in Fig. 30 like methods for running traps. We do this in order to show our readers some of the mistakes which it is natural for a beginner to make, and which he can the better avoid after comparing wrong constructions with correct. The common quarter bend is a compact fitting as No. 1 will show, and the mistake often made is in giving it the long sweep shown in No. 2, although there are special fittings made after the manner of No. 2. The same fault is often found in the drawing of eighth and other bends. In drawing the quarter bend, first run the horizontal and vertical lines, then with the compasses set on a center close to the intersection of the two inside lines, describe the curves so that they will run smoothly into the respective lines. Of course both curves are struck from the same center. Many times the eighth bend will be used between a Y branch and a straight run of pipe. In this case, draw in the lines for the Y branch and the straight line, then connect these lines with the proper curve. Not until this is done should the hub on the branch or on the bend be drawn. Now with reference to

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Model for Students to Work Out-Combinations of Pipe and Fittings as we give it. This should be drawn on same scale, at least no smaller.

the running trap of Fig. 30. The common fault in drawing this fitting is to make the curve of the trap too low down, that is, to give the trap a much deeper seal than is it really has. Another fault shown in No. 2 as compared with No. 1. is the length of the straight lines connecting the vent hubs with the trap. As seen in No. 1, these hubs set close to the trap, and are close together. We have taken up the construction of these particular fittings in order that use may be made of the instructions given in working out the exercise in drawing which we give in Fig. 31. We would suggest that with this figure as a model the student work out the combination of pipe and fittings as we give it, and on the same scale, or at least no smaller

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